Example embodiments relate to a temperature sensor, and more particularly, to a temperature sensor to compensate for a change in an output characteristic due to varying temperature.
Even if other conditions are unchanged, the amount of current flowing through a transistor, which is a semiconductor device, varies according to an ambient temperature around the transistor since electron mobility varies with temperature. In general, since electron mobility decreases as temperature increases, if temperature increases, the amount of current flowing through the transistor decreases.
Temperature sensors, based on the principle that the amount of current varies according to the temperature of a transistor, may detect a change in the amount of current flowing through a bipolar transistor due to varying temperature by using a current mirror. The temperature sensors convert the detected change in the amount of current into a corresponding voltage that is an analog voltage, convert the corresponding voltage into a digital signal by using an analog-to-digital converter, and display a temperature corresponding to the digital signal by using a counter.
Such a temperature sensor includes a bipolar transistor, a current mirror, an analog-to-digital converter, and a counter, all of which include transistors. Accordingly, as an ambient temperature around the temperature sensor increases, not only does the amount of current flowing through the bipolar transistor change, but also the amount of current flowing through the current mirror, the analog-to-digital converter, and the counter change.
Ideally, a temperature displayed by the counter varies linearly as temperature increases linearly. However, due to the aforementioned temperature characteristics of the bipolar transistor, the current mirror, the analog-to-digital converter, and the counter, there is always a difference between the displayed temperature and the actual temperature.